The note that tells the model what it can now see: "[You can now see: Ada's screen]". Several sources are named in the
order given, joined with ", " ("[You can now see: Screen, Camera]").
A meeting's bridge engine sends it right before the first frame of a camera or screen new to the model's session.
A call's video source arbiter sends it when the sources in view change while it chooses among more sources than the
model takes, naming every source in view.
Parameters
sourceLabels: string|readonlystring[]
The human-readable name of the source now in view, or of each source in view (at least one), put in
as given.
The note that tells the model what it can now see: "[You can now see: Ada's screen]". Several sources are named in the order given, joined with ", " ("[You can now see: Screen, Camera]").